Characterization of different crystal forms of the alpha-glucosidase MalA from Sulfolobus solfataricus.

Research paper by Heidi Asschenfeldt HA Ernst, Martin M Willemoës, Leila L Lo Leggio, Gordon G Leonard, Paul P Blum, Sine S Larsen

Indexed on: 03 Mar '06Published on: 03 Mar '06Published in: Acta crystallographica. Section F, Structural biology and crystallization communications


MalA is an alpha-glucosidase from the hyperthermophilic archaeon Sulfolobus solfataricus. It belongs to glycoside hydrolase family 31, which includes several medically interesting alpha-glucosidases. MalA and its selenomethionine derivative have been overproduced in Escherichia coli and crystallized in four different crystal forms. Microseeding was essential for the formation of good-quality crystals of forms 2 and 4. For three of the crystal forms (2, 3 and 4) full data sets could be collected. The most suitable crystals for structure determination are the monoclinic form 4 crystals, belonging to space group P2(1), from which data sets extending to 2.5 A resolution have been collected. Self-rotation functions calculated for this form and for the orthorhombic (P2(1)2(1)2(1)) form 2 indicate the presence of six molecules in the asymmetric unit related by 32 symmetry.